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<H2> Table of Contents
</H2>

<PRE>
   <A HREF="#TICTOC User's Guide">TICTOC User's Guide</A>
      <A HREF="#Abstract">Abstract</A>
      <A HREF="#Summary">Summary</A>

</PRE>

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<A NAME="TICTOC User's Guide"></A>
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<H1> TICTOC User's Guide
</H1><HR SIZE=3 NOSHADE><P><BR><BR><BR>
   Last revised on 2002 DEC 13 by E. D. Wright.
<P>
 
<BR><BR>
<A NAME="Abstract"></A>
<p align="right"><a href="#top"><small>Top</small></a></p>
<H2> Abstract
</H2><HR ALIGN="LEFT" WIDTH=50% ><P><BR><BR>
   TICTOC is a cookbook program that demonstrates how to use Toolkit
   routines to convert between different time representations.
<P>
 
<BR><BR>
<A NAME="Summary"></A>
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<H2> Summary
</H2><HR ALIGN="LEFT" WIDTH=50% ><P><BR><BR>
   The TICTOC `cookbook' program illustrates the use use of the two SPICE
   time conversion routines:
<P>
 
<DL><DT>
<B>
 <a href="../cspice/str2et_c.html">str2et_c</a>
</B><BR><BR>
<DD>
</DL>
<DL><DT>
<B>
 <a href="../cspice/et2utc_c.html">et2utc_c</a>
</B><BR><BR>
<DD>
</DL>
   These routines convert between UTC and ET representations of time:
<P>
 
<DL><DT>
<B>
 UTC
</B><BR><BR>
<DD>
 is a string representation of Universal Time Coordinated, which may be
in calendar, day of year, or Julian date format. UTC time strings are
human-readable and thus suitable as user input.<BR>
</DL>
<DL><DT>
<B>
 ET
</B><BR><BR>
<DD>
 which stands for Ephemeris Time, is the double precision number of
ephemeris seconds past Julian year 2000. ET time is used internally in
SPICELIB routines for reading ephemeris files. (The term ``Barycentric
Dynamical Time'' - TBD - is widely used in place of ET.)<BR>
</DL>
   When you run TICTOC, it outputs several examples of UTC time strings and
   their corresponding ET times. However, successful execution of the
   program is only the first step in learning about CSPICE time conversion.
   Read the TICTOC source code for CSPICE routines time conversion usage
   examples. Also, refer to Time Required Reading (<a href="../req/time.html">time.req</a>) and the
   <a href="../cspice/str2et_c.html">str2et_c</a> and <a href="../cspice/et2utc_c.html">et2utc_c</a> module headers for additional information.
<P>
 
   TICTOC requires a leapseconds kernel to run; an example leapseconds
   kernel, 'cook_01.tls' exists in the CSPICE data directory.
<P>
 
   The following is a sample session of a TICTOC execution.
<P>
 
   Please note: FORTRAN and C versions of the program may output numerical
   values in slightly different formats.
<P>
 
   It is assumed the kernel files used by TICTOC exist in the current
   directory (i.e. the directory from which your execute TICTOC). This
   particular session was run on an Intel box using the LINUX operating
   system.
<P>
 
<PRE>
 
                    Welcome to TICTOC
 
   This program demonstrates the use of the CSPICE
   time conversion utility routines: <a href="../cspice/str2et_c.html">str2et_c</a> and <a href="../cspice/et2utc_c.html">et2utc_c</a>.
 
   Enter the name of a leapseconds kernel file: cook_01.tls
 
   Working ... Please wait.
 
 
         Example UTC time      :  9 JAN 1986 03:12:59.22451
 
         Corresponding ET      :  -441103565.591323
 
         UTC calendar format   :  1986 JAN 09 03:12:59.225
         UTC day of year format:  1986-009 // 03:12:59.225
         UTC Julian date format:  JD 2446439.634
 
   Continue? (Enter Y or N): Y
 
         Example UTC time      :  1/9/86 3:12:59.22451
 
         Corresponding ET      :  -441103565.591323
 
         UTC calendar format   :  1986 JAN 09 03:12:59.225
         UTC day of year format:  1986-009 // 03:12:59.225
         UTC Julian date format:  JD 2446439.634
 
   Continue? (Enter Y or N): Y
 
         Example UTC time      :  86-365//12:00
 
         Corresponding ET      :  -410313544.816091
 
         UTC calendar format   :  1986 DEC 31 12:00:00.000
         UTC day of year format:  1986-365 // 12:00:00.000
         UTC Julian date format:  JD 2446796.000
 
   Continue? (Enter Y or N): Y
 
         Example UTC time      :  JD 2451545
 
         Corresponding ET      :  57.183927
 
         UTC calendar format   :  2000 JAN 01 12:00:00.000
         UTC day of year format:  2000-001 // 12:00:00.000
         UTC Julian date format:  JD 2451545.000
 
   Continue? (Enter Y or N): Y
 
         Example UTC time      :  77 JUL 1
 
         Corresponding ET      :  -710164751.815897
 
         UTC calendar format   :  1977 JUL 01 00:00:00.000
         UTC day of year format:  1977-182 // 00:00:00.000
         UTC Julian date format:  JD 2443325.500
 
   Continue? (Enter Y or N): Y
 
         Example UTC time      :  1 JUL '29
 
         Corresponding ET      :  930830457.184117
 
         UTC calendar format   :  2029 JUL 01 00:00:00.000
         UTC day of year format:  2029-182 // 00:00:00.000
         UTC Julian date format:  JD 2462318.500
 
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